1. Field of the Invention
The present invention relates to a method of forming a silicon-containing insulating film and to a semiconductor device manufacturing method. More particularly, the present invention relates to a method suitable for forming a silicon-containing insulating film that has a low dielectric constant and can easily be etched.
2. Description of the Prior Art
In recent years, the speed of the electronic equipment has increased, and hence higher operational speeds are required of the semiconductor devices employed in the electronic equipment. One method that can accelerate the operational speed of the semiconductor device, uses a film having a low dielectric constant as the interlayer insulating film in the semiconductor device. Therefore, various interlayer insulating films having low dielectric constants have been studied recently.
It is also desired that the interlayer insulating film of the semiconductor device have not only a low dielectric constant, but also can easily be etched. If a film can easily be etched, the film is said to have an easy etching workability.
This is because if the etching workability of the interlayer insulating film is inferior, a fine opening (e.g., contact hole and via hole) or groove (e.g., damascene trench) cannot be formed in the film, which in turn poses an obstacle to providing devices having highly integrated structures.
It is an object of the present invention to provide a method of forming a silicon-containing insulating film, which is capable of forming an insulating film exhibiting both a low dielectric constant and an easy etching workability.
Another object of the present invention is to provide a semiconductor device manufacturing method which includes forming an interlayer insulating film exhibiting both a low dielectric constant and an easy etching workability.
Yet another object of the present invention is to provide a semiconductor device that has an interlayer insulating film that exhibits both a low dielectric constant and an easy etching workability.
According to the film forming method of the present invention, a silicon-containing insulating film is formed on a substrate by forming a plasma of a reaction gas that contains H2, an oxidizing gas, and a compound having a siloxane bond (Sixe2x80x94Oxe2x80x94Si) and a Sixe2x80x94R bond, wherein R is an alkyl group, and contacting the substrate with the plasma to form the silicon-containing insulating film on the substrate.
The R (alkyl group) contained in the compound having the siloxane bond (Sixe2x80x94Oxe2x80x94Si) and the Sixe2x80x94R bond is incorporated into the silicon-containing insulating film. Since the Sixe2x80x94O bond in the film is not connected with the substrate where the R (alkyl group) is present, the dielectric constant at those positions is lowered compared to the remainder. Therefore, the dielectric constant of the overall film can also be lowered, and thus the silicon-containing insulating film having a low dielectric constant can be formed.
Also, since H2 in the reaction gas bonds to C (carbon) in the film to generate an R group (alkyl) such as CH3, etc., the number of Sixe2x80x94C bonds or Cxe2x80x94C bonds in the film can be reduced. Because the Sixe2x80x94C bonds or the Cxe2x80x94C bonds reduce the etching workability of the film, the silicon-containing insulating film formed as above has improved etching workability.
In addition, the dielectric constant of the silicon-containing insulating film is further lowered by the presence of the R group (alkyl) that is generated by the reaction of H2 in the reaction gas and C (carbon) in the film. That is, since the Sixe2x80x94C bonds in the film are occupied by these R groups (alkyl), the dielectric constant of the film can be lowered.
Also, the R group (alkyl) generated by the reaction of H2 in the reaction gas and C (carbon) in the film tends to remain in the film even when the film forming temperature is relatively high. As a result, even if the film forming temperature is set high, the silicon-containing insulating film having a low dielectric constant can be formed.
It should be noted that a compound having a siloxane group (Sixe2x80x94Oxe2x80x94Si) and a Sixe2x80x94OR group (OR is alkoxyl), or a compound having a R group (alkyl) can be employed in place of the above compound having the siloxane group (Sixe2x80x94Oxe2x80x94Si) and the Sixe2x80x94R group (R is alkyl). Employing these compounds can achieve the same advantage as those descried above.
According to the semiconductor manufacturing method of the present invention, the above film forming method is employed in forming an interlayer insulating film. The interlayer insulating film thus formed exhibits both a low dielectric constant and an easy etching workability. The former contributes to reduce parasitic capacitances between the copper wirings, while the latter facilitates formation of fine openings such as contact holes and via holes.
The semiconductor device manufactured in accordance with this method therefore has a high operating speed and a highly integrated structure.